The Genie in the Admixture Bottle

Eastern Precast of Hatfield, Pa., an Oldcastle company, is using a new approach to designing plants: engineering them around the use of self-consolidating concrete (SCC). Under the leadership of Area Manager Chuck Galbraith, Oldcastle designers have incorporated SCC into practically all types of their precast production processes.

In the course of planning for a plant transformation, Oldcastle engineers have tailored their production layouts to three key elements of SCC workability.

Due to the use of SCC, workers minimize the use of vibrators, which can help to reduce the ambient noise level in the casting area. They're able to cut down on the amount of raking. Also, because SCC requires little handling during placement, crews use fewer tools and trowels. Finally, much less cleanup is required after a pour. In many cases, managers can reduce the size of crews, increase the number of elements cast during a single pour, or increase pour frequency.

Galbraith had set a production goal to maximize most precast plants' most common constraint: the capacity of the bucket hopper. To do this, the engineering team decided to employ two 4-cubic-yard pan mixers.

Another important production constraint that Galbraith wanted to minimize was mixer cleanout time. Designed to reduce any unnecessary labor costs, high-performance stainless-steel liners will lessen the need for cleanout at the end of the chute. Also, a second discharge chute was added so that a plant operator could direct material to a mobile concrete hauler.

The article includes a production checklist for an SCC-engineered plant.